PISCIVORY AND CANNIBALISM IN ARCTIC CHARR

Piscivory and cannibalism in Arctic charr, Salvelinus alpinus, were studied in three lakes in northern Norway: Guolasjavri, which contains only charr, Takvatn, where Arctic charr coexist with three-spined sticklebacks, Gasterosteus aculeatus and brown trout, Salmo trutta, and Stuorajavri, where whitefish, Coregonus lavaretus dominate a fish community containing six species. The prevalence of piscivory in the Arctic charr populations generally increased with increasing predator size. In all three lakes, many charr larger than 20 cm were piscivorous, but the extent of piscivory and cannibalism varied. The greatest prevalence of cannibalism was found in Guolasjavri, where 27% of charr greater than 20 cm in length had fed upon smaller conspecifics. In Takvatn, 5% of charr larger than 20 cm were cannibalistic, and an additional 9% had eaten three-spined sticklebacks. In Stuorajavri, up to 74% of the charr greater than 20 cm had eaten whitefish but cannibalism was not recorded. The possible role of cannibalism in population regulation within Arctic charr populations is considered.